avoid breakage if somebody wrongly defines empty feature test macros

[musl] / include / unistd.h

diff --git a/include/unistd.h b/include/unistd.h
index 9ac4765..bb741e4 100644 (file)
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -149,7 +149,7 @@ void swab(const void *__restrict, void *__restrict, ssize_t);
 #endif
 
 #if defined(_GNU_SOURCE) || defined(_BSD_SOURCE) \
- || (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE < 700)
+ || (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE+0 < 700)
 int usleep(unsigned);
 unsigned ualarm(unsigned, unsigned);
 #endif